car overheating and leaking?

My 2002 lancer es(190,000 miles)started overheating. i pulled over checked under the hood and couldnt see a leak but there was a brownish clearish fluid all over the place. It looks like it came from the front of the engine compartment maybe the radiator, But the coolant reservior shows that my coolant levels are good. What might this fluid be and any idea whats causing it to overheat?